1. Technical Field
The following description relates to one or more image forming devices configured to form an image by using a rotational body, more particularly, to one or more image forming devices configured to store a correction parameter for canceling a deviation of an image forming position caused due to unevenness of a rotational speed of the rotational body, and to correct the image forming position based on the correction parameter.
2. Related Art
An electrophotographic image forming device is configured to form an electrostatic latent image by optically scanning a surface of a rotating photoconductive body, and to transfer onto a recording sheet an image obtained by developing the electrostatic latent image with toner. According to such an image forming device, it is possible to form an image (including an electrostatic latent image) with a constant distance (scanning line interval) between any adjacent two of scanning lines by sequentially performing optical scanning at scanning timings of a constant time interval when the photoconductive drum rotates at a constant rotational speed. However, the photoconductive body is actually rotated at a periodically varying rotational speed. Therefore, unevenness of scanning line intervals might result in a low-quality image.
In view of the above problem, Japanese Patent Provisional Publication No. 2000-284561 discloses an image forming device configured to previously determine actual phases in a rotational movement of a photoconductive drum and a correction value at each of the phases, and to store on a memory the determined correction value as a correction parameter. The correction value denotes a correction value for scanning timing that is required for correcting a scanning line interval at each phase to be a standard line interval. When an image forming instruction is issued, the image forming device estimates a phase in the rotational movement of the photoconductive drum based on a phase of an original point of the photoconductive drum detected by an original point sensor and an internal clock provided in the image forming device. Then, the image forming device sequentially reads out a correction value corresponding to the estimated phase from the memory. Subsequently, based on the correction value as read out, the image forming device corrects the scanning timing for each scanning line, and corrects each scanning line interval to be the standard line interval.